This brief explores recent progress in the area of polysaccharides and their composites and nanocomposites. It is a complete resource for the evolving field of polysaccharide based biomaterials and their applications in different fields. The volume focuses on their composition, properties, characterization, chemistry and applications and also highlights recent developments in polysaccharide based composites and nanocomposites spurred by advances in polymer technology and biotechnology. Divided into different sections featuring alginates, carrageenans, cellulose, starch, chitin, chitosan, gums, etc, each chapter presents chemical, physical, and biological attributes, and reviews the recent research performed such as drug carriers, selective water absorption materials from oil-water emulsions, purification of water, biomedical applications, etc. The authors hope that this brief will help to inspire scientists towards novel sources for chemicals, materials, and energy in the years to come.